1. Technical Field of the Invention
This invention generally relates to digital recording, playing, and playback of previously recorded audiovisual (A/V) signals. This invention more particularly relates to a method and apparatus for receiving broadcast entertainment-type data, such as packetized digital video, audio, conditional access, and system time signals transmitted in a direct broadcast satellite or digital video broadcast (DVB) system, and for storing the received data in an encrypted format, until viewing is desired by the user.
2. Description of Related Art
Conventional communications systems include a receiver for receiving and processing transmitted waveforms. One type of receiver is part of a “wireless digital television.” Wireless Digital Television allows consumers to receive, directly in their homes, numerous channels broadcast from a set of satellites. The receiver includes a small satellite dish connected by a cable to a set-top box (STB) or an integrated receiver-decoder (IRD), which are used as interchangeable terms in the art. The satellite dish is aimed toward the satellites, and the STB is connected to the user's television in a similar fashion to a conventional cable-TV decoder.
On the transmission side, video, audio, and related information data signals are digitally encoded into a packetized data stream using a number of algorithms. The encoded data stream, which includes overhead for error correction, is modulated to Ku-band frequency, transmitted to the satellite, and relayed from the satellite to the satellite dish. The satellite dish shifts the Ku-band signal down to an L-band signal that is transmitted through the cable to the STB.
In the STB, front-end circuitry receives the L-band signal and converts it to the original digital data stream of video, audio, and related information signals. The digital data stream is fed to video/audio decoder circuits that perform the main video/audio processing functions such as de-multiplexing and decompression. A micro-controller controls the overall operation of the STB, including the selection of parameters, the set-up and control of components, channel selection, viewer access to different programming packages, blocking certain channels, and many other functions. The compression and decompression of packetized video signals may be accomplished according to the Motion Picture Expert Group (MPEG) standards and the compression and decompression of audio signals may be accomplished according to the Motion Picture Expert Group (MPEG) standards or the Dolby™ Digital (or AC-3) standard. Thus, the STB unit typically includes an MPEG-1 or MPEG-2 video decoder and an MPEG-1, MPEG-2, or Dolby™ Digital (or AC-3) audio decoder in order to decompress the received compressed video and audio. The video and audio decoders can be on the same or separate chips.
A transport processor of the STB outputs video and audio data to a number of destinations, including audio and video decoders, ports, memories, and interface devices, such as a digital VHS (DVHS) interface. The STB may send the same audio and video data to different destinations.
Using a conventional STB, when a user wishes to view a pay-per-view (PPV) event, the user (1) must decide in a relatively short period of time (one half-hour or less) whether the user wants to view the PPV event; (2) must be available to view the PPV event when the programming is shown; (3) must wait, usually until the next half-hour boundary, for the PPV event to begin; and (4) must watch the PPV event in real time. These time constraints unnecessarily burden the potential viewer of a PPV event.